Biology Chapter 6: Tissues

Chapter 6: Tissues

• Living organisms are made of cells.
• In unicellular organisms, one cell performs all functions.
• In multicellular organisms, cells specialize and work together in groups.
• These organized groups of cells that perform a specific function are called tissues.

Plant and Animal Tissues

• Plant cells are stationary, so they have lots of supportive tissue and are often non-moving.
• Animal tissues are more specialized and move around for things such as food and shelter.
• Plant growth is limited to specific regions; animal growth is more uniform, not limited to specific regions.
• Plant tissues are classified by their ability to divide: growing (meristematic) or non-dividing (permanent).
• Animal tissue types are mostly living: epithelial, connective, muscle, and nervous.

Plant Tissues

• Meristematic tissue: Composed of actively dividing cells, responsible for growth in specific regions of the plant (e.g., tips of stems and roots).
  • Apical meristem – growth in length
  • Lateral meristem – increase in girth.
  • Intercalary meristem – short segments between permanent tissues
• Permanent tissue: Formed from meristematic tissue.
  • Simple permanent tissue: Consist of similar cells (Parenchyma, Collenchyma, Sclerenchyma)
    • Parenchyma: Stores food, have thin walls, and are loosely arranged.
    • Collenchyma: Provides flexible support and has unevenly thickened walls.
    • Sclerenchyma: Dead cells with thick, lignified walls, providing support; found in hard parts of plants
  • Complex permanent tissue: Made of different cell types. (Xylem and Phloem)
    • Xylem: Transports water and minerals.
    • Phloem: Transports food.

Animal Tissues

• Epithelial tissue: Covers surfaces, lines body cavities, and forms glands; involved in protection, secretion, and absorption.
  • squamous: flat, thin cells
  • stratified: layered cells
  • columnar: pillar-like, elongated cells
• Connective tissue: Supports and connects tissues in the body (e.g., blood, bone, cartilage, adipose tissue).
  • Blood: Transports substances throughout the body.
  • Bone: Supports and shapes the body.
  • Cartilage: Smooths bone surfaces and provides support (e.g., ears, nose).
  • Adipose tissue: Stores fat for energy storage and insulation.
• Muscle tissue: Responsible for movement.
  • Striated (skeletal): Attached to bones, used for voluntary movements.
  • Smooth (visceral): Found in body organs, used for involuntary functions.
  • Cardiac: Found in the heart, responsible for rhythmic contractions.
• Nervous tissue: Composed of neurons; responsible for communication and coordination in the body.

Tissue Activity

• Onion bulb root experiment: Demonstrates growth in plant parts.
• Examining plant cross sections using stains and microscopes: Allows observation of different tissue structures and cell types
• Examine plant parts under microscope: reveals epidermal tissue, cell types and structure.